Giant Killers is back for our 12th annual metrics-based forecast of big upsets in the NCAA Tournament. As always, we have analyzed all six Giant vs. Killer matchups in each of the four regions of the bracket. (Remember: A Giant Killer is any team that defeats an NCAA Tournament opponent seeded at least five spots higher in any round.) And we have sorted them into our longtime categories of Best Bets, Worth a Long Look, Not Completely Crazy and Stay Away, which you can use according to how your pool rewards longshots.